Spring device



April 12, 1960 MATHER ETAL SPRING DEVICE Filed May 3, 1955 2 Sheets-Sheet 1 g ad ,714

INVENTORS. Glen E. Mather Donald C. Green THE IR A TTORNE Y8 April 12, 1960 Filed May 3 955 G. E. MATHER L 2,932,506

SPRING DEVICE 2 sheetsu eet 2 p INVENT /en E. May

000/0 62 een THE/R A RME Ys Length 2,932,506 Patented Apr. 12, 1960 SPRING nnvlcn Glen E. Mather and Donald C. Green, Logansport, Ind,

assignors to Rockwell-Standard Corporation, a corporation of Pennsylvania Application May 3, 1955, Serial No. 505,582

24 Claims. (Cl. 267-=44) This invention relates to a spring device effective as a highly elastic leaf or beam in supporting a load, and more particularly, relates to an adjustable leaf load spring whose beam depth in cross section can be varied while the spring is supporting the load to stiffen the same against excessive deflection under load. An illustrative embodiment of the invention is shown in the accompanying drawings in which:

Figures 1 and 2 are top plan and side elevational views of the tension member of the spring device;

Figure 3 is a fragmentary end section of the complete spring device;

Figure 4 is a transverse section taken along the lines lV-IV of Figure 3;

Figure 5 is a sectional view similar to Figure 4 but showing the spring device inflated;

Figure 6 is a view similar to Figure 4 but showing a modified form of the fabricated spring; and

Figure 7 is a perspective view, partially diagrammatic, of the spring device applied in perspective to a vehicle suspension.

in more specific reference to Figures 1-5 and 7 of the drawings, a fabricated flat longitudinal leaf spring 10 is shown having an upper tension strip or leaf 11 and a lower compression strip or leaf 12 which are spaced apart vertically from one another so as to define a shallow, longitudinally extending, included chamber '15 forming the hollow interior of the spring device 10. The spring device '10 has its opposite end portions turned to form a pair of bent integral spring eyes 13 and the spring device has a camber or curve of conventional shape in its body portion.

The long edges of the compression leaf 12 are bent upwardly to form flanges 12a so as to present a shallow channel cross section, and the flanges are seam welded as at 14 to the opposite sides of the tension leaf 1'1 and the oppositeextremities of the leaf =12 are similarly welded at 14 to the underside of the tension leaf 1:1. Accordingly, the chamber 15 within the hollow interior of the fabricated spring device 10 has a continuous line of. welding at'the seams and forms a fluid-tight chamber. Ad-

jacentone of the eyes 13, a vertically disposed opening 16 is formed in the tension leaf 11 to communicate with 'hose receiving fitting 17 is secured to the leaf 11 about the mouth of the opening 16, being welded thereto at 18 to form a fluid-tight joint for charging and relieving the pressure therein;

The following is given as an example of the dimen sions of the upper tension leaf 11 which is preferably strip steel:

48" Width 6" Thickness 0.375"

" The following is given as an example of the dimeneel ' sions of the lower compression leaf 12 which is preferably strip steel:

Length 46" Width of channel of Thickness Q 0.125"

From the foregoing dimensions, it is apparent that the lower compression leaf His only approximately one-third as thick as the upper tension leaf 11, andit is further apparent that the Width to thickness ratio (4821) of the springy lower leaf is proportioned such that the leaf is flexible transversely and can crown or bulge between its opposite long edges in a direction of bow at right angles to the lengthwise bow or camber of the spring device 10 between its opposite ends.

Internal inflation of the chamber 15 in the spring device 10 produces such a crowning or bulging action of the lower leaf 12 according to Figure 5. This action obviously increases the beam depth of the spring device 10 rendering the calculated moment of inertia of the cross section considerably greater and greatly improving the beam stiffness of the spring device 10 regardless of its application as either a semielliptic spring, a cantilever spring, or otherwise.

In Figure 6, a modified showing 10a of the spring device of the foregoing figures is illustrated. The modified spring device 10a is a flat, one-piece member formed of seamless steel tubing thicker at one side than the other such that the upper, relatively thick tension leaf and the relatively thinner compression leaf portions 19; jointly define an included inflatable chamber 15 substantially identical in appearance to the inflatable chamber of the spring device 10 of the preceding figures. Internal inflation of the spring device ltla of Figure 6 results in an improved and deepened beam section the same as shown in Figure 5.

In Figure 7, the composite spring device 10 is shown embodied in a semielliptic, longitudinal leaf spring suspension for a load carrying supported structure comprising a longitudinally extending vehicle side rail 20 of general U-shaped channel section and being inwardly open with respect to an opposite side rail (not shown). A similar spring device =10 may be provided for the opposite side rail. The illustrated side rail 20 at its rear end has a bracket 22 mounted to the inside of the lower'one of the opposed legs of the U-shaped channel. The bracket 22 fixedly carries a pivot pin 24 swingably supporting a depending double-link shackle 26 which carries another pivot pin 28 at its lower swinging end. The pivot pin 28 is received in the eye 13 at the rear end of the composite spring device It). In the front eye 13 at the opposite end of the spring device 10*, another pivot pin 30 is received which is carried by a depending pair of apertured spaced apart ears on a bracket 32 mounted to the underside of the side rail 20.

Between its opposite end portions, the spring device 10 carries a steel pillow block 34 which supports a hollow axle housing 36. The axle housing 36 receives a longitudinally extending drive axle ,38 jpurnaled therein and at its outer end, the housing 36 carries a brake backing plate 40 for the brake of a wheel (not shown) driven by the axle 38. A frustum-shaped rubber jounce bumper member 41 is mounted to the underside of the side rail 2%) in a position of vertical alignment above the axle housing 36 so as to engage a bumper plate 42 which is rigidly carried by the housing 36 and which moves conjointly in the path of motion therewith. A powerful permanent magnet 44 is also carried by the bumper plate 42 at a position offset from the latters point of engage ment with the bumper 41. A pair of threaded ,U-bolts 46 is provided which encircle the upper surface of the bumper plate 42 and hang downwardly below the axle housing 36. ,The threaded end portions of the U-bolts able hydraulic fluid or non-viscous liquid is automatically 7 communicated into andout of the hollow interior thereof and the fitting '17 receives the moving end of a flexible rubber hose connector 50 which is secured fast at its oppo- -site end to a stationary fitting 52 mounted within the :channel of the vehicle side rail 20. The fitting 52 is which may be securely mounted to the frame structure .supported by the frame side rail 20. A rotary fluid pump 58 included in the control component 57 has a pair of inner and outer lobed rotors which differ by one in the number of lobes thereon and which are arranged for rotation such that the included chambers 60 therebetween trap pressure fluid to conduct it in quantities by positive displacement from a pump intake supply conduit 62 into a pressurized discharge conduit 64 connected to theT fitting 56. Interposed in the discharge conduit 64, a pressure blow-off valve fitting is provided at 66 for by-passing fluid above a predetermined pressure back into the intake conduit 62. The pump intake supply conduit 62 draws suction'from a reservoir tank 68 containing a supply of pressure fluid at atmospheric'pressure.

Another pump by-pass fitting in the form of a valve 'casing 70 is connected between one leg of the T-fitting 56 and the pump intake supply conduit 62. The valve casing 70 includes a port therein controlled by means of a needle valve 72. A valve positioning electric motor 74 drives the needle valve into its appropriate adjusted positions for regulating the fluid pressure by means of an interposed pinion and rack connection at 76. The motor 74 is energized and reversibly controlled in its actuatlon by means of a combined amplifier and motor control device diagrammatically indicated at 78. The amplification portion of the device 78 actuates the motor control portion so as to keep the regulating valve ad- ]U Si6d in response to electrically generated signals received through a cable 80, the cable 80 being connected .to a stationary sensing unit 82 disposed vertically above the movable axle supported permanent magnet 44. The .senslng unit 82 may include an induction coil pickup ele' ment 83 ,therewithin which is effective to register and transmit an electromagnetically induced voltage from the magnet 44 and communicate the same to the amplifier and motor control device 78. A pair of gusset plates 86.welded to the frame side rail 20 carries a mounting bracket 84 which supports the sensing unit 82 in a fixed position above the magnet 44.

Under increasing load on the load carrying supported part and the side rail 20, the spring device 18 deflects so as to bring the permanent magnet unit 44 into closer proximity to the sensing unit 82. The changing electromagnetic field linking the two units 44 and 82 thus becomes relatively stronger in its action on the sensing unit and on the amplifier device 78 when the distance between the units 44 and 82 is materially diminished, or conversely, that field weakens when the parts occupy widely spaced positions and produces only feeble signals to be fed to the amplifier device.

'In operation, any change causing the suspension parts 44 and 82 to move into and take working positions which are either widely spaced apart or spaced materially closer together is sensed by the device 78 which in turn causes selective directional rotation of the motor 74. For example, when parts 44 and 82 move apart, device 78; C011,-

trols directional rotation of motor 74 to move the needle valve 72 away from its seat and when parts 44 and 82 move toward each other, device 78 controls directional rotation of motor 74 so as to move the needle valve 72 toward the valve seat. The rotary pump 58 continually circulates fluid through the path including the bypass valve casing 70 and, as the needle valve 72 is adjusted in a direction toward its seat in the by-pass, pump pressure builds up the back pressure within the hollow interior of the fluid-tight spring device 310.

This constantly by-passing system of circulation through the valve casing 70 with the needle in its adjusted positions enables a precise degree of fluid pressure regulation controlled automatically in. dependence. upon the axle-connected and frame member-connected parts 44 and 82 which, as these members reciprocate, cooperate to regulate that pressure as an inverse function of the distance between the members. Changes in the regulated pressure directly adjust the internal'back pressure or inflation pressure of the spring chamber 15 which accommodates thereto through the bi-direc'tio'nal fitting 17 which, as noted, is the common communication function- .ing both. to charge and to relieve inflation pressure as appropriate in the former. 7

Under inflation pressure, the compression leaf 12 bulges or crowns throughout the greater part of .the length of the spring device 10 so as to increase its beam depth and materially increasethe stiffness and resistance thereof to deflection. Accordingly, the spring 18 resists being forced toward the side rail 20 in direct proportion to its closeness thereto and, when inflated, tends to separate therefrom. In case two trans- .versely aligned spring devices 10 are located on opposite sides of a vehicle body, the spring devices will automatically tend to provide an anti-rollstability to the vehicle inasmuch as body roll to either-side is naturally attended by an approaching of the load carrying side rail and the spring suspension toward one another. A stiffening resistance to roll, therefore, results and the suspension under its internal pressurization tends to lift the side rail thereabove rather than collapse and allow the same to lower.

As herein disclosed, the adjustably stiflFenable spring invention is shown embodied ina vehicle spring suspen- ;sion. It is evident that the-stiffening spring feature has application to other spring suspensions embodied in load carrying structures of any description in which the load is subject to variance.

While we have described certain presently preferred embodiments of our invention, it is to be understood that it may be otherwise embodied within the scope of the appended claims.

We claim:

1. A load carrying supported part, a leaf type load spring part therefor having an elongated flexible wall .portion forming one side of a longitudinallyextending,

inflatable chamber within the leaf of the load spring part, flexible connector means disposed between and secured at its opposite ends to the parts for introducing pressure fluid into the inflatable chamber to bulge said flexible leaf being at least approximately three times thicker, and bidirectional fluid fitting means communicatively connected to the interior of the leaf spring member to charge and relieve the inflation'pressure thereof so" as'to selectively bulge the wall and thereby apply tension strain substantially exclusively on the leaf already under compression.

3. A fluid inflatable spring member formed with a longitudinally extending hollow interior and having a bulging compression wall on one side thereof, having a stiff, thicker tension wall at the opposite side which in tegrally carries a spring eye at each of its ends, and having a bidirectional fluid fitting means mounted to the tension wall and connected to the interior of the spring member to charge and relieve the inflation pressure thereof so as to bulge the thinner wall and thus apply tension strains to the compression wall instead of applying further tension strains to the already tensioned thicker wall.

4. In combination, first and second relatively reciprocable suspension parts, said first part comprising an internally inflatable leaf spring part having a bulgable wall portion and a fluid-tight interior, a source of regulated inflating fluid connected to the interior of the leaf spring part, and means for automatically regulating the pressure of the inflating fluid in accordance with the distance between the parts as they reciprocate.

5. In combination, first and second relatively reciprocable suspension members, said first member comprising an internally inflatable leaf spring member having a bulgable wall portion and a fluid-tight interior, a flexible hose having one end structurally fast to said second member and having the opposite end fast to and connected to the interior of the first member, and fluid pressure regulating means communicatively connected to said one end of the flexible hose to apply and to automatically regulate the magnitude of the inflating pressure applied to the spring through the hose in proportion to the direct proximity of the members to one another.

6. In combination, first and second relatively reciprocable suspension parts at least one of which elastically deflects during relative reciprocation and stiflens when it swells under pressure, said first part having magnet means mounted thereon which confronts the second part and which directs theretoward a magnetic field which varies in its effect as a function of the distance or proximity between parts, fluid means connected to pressurize and stiffen said one part, and means onthe second part sensitive to the effectiveness of the magnetic field for controlling the fluid means and causing a stiffening of the said one part against deflection as a function of the proximity of the parts.

7. In a suspension, first and second relatively reciprocable parts, at least one of which elastically flexes between its ends during relative reciprocation and which, when straightened, is caused to separate from the other part, said first part having magnet means mounted thereon which confronts the second part and which directs theretoward a magnetic field which varies in its effect as a function of the proximity between parts, fluid means connected to pressurize and stiffen said one part, and actuating means sensitive to the effectiveness of the magnetic field for controlling the fluid means and causing said one part to straighten and separate from an attained position thereof of near proximity with respect to the other part.

8. In combination, first and second relatively reciprocable suspension members, said first member comprising an internally inflatable spring member having wall portions of different gauges on opposite sides of a fluid-tight interior of noncircular cross section, a source of normally by-passed circulating liquid connected to the interior of the first member, and fluid pressure regulating means including a valve portion for blocking said by-pass to immediately increase the liquid back pressure in the interior of the first member for bulging the thinner gauge wall portion.

9. In combination, first and second relatively reciprocable suspension members, said first member comprising a generally fiat liquid-filled spring member having vertically spaced flat sides of differing gauges on opposite sides of a fluid-tight interior, a source of normally bypassed circulating liquid having means connecting it to the liquid inside the first member comprising a. fitting connected to said first member at the top of the upper side thereof, and fluid pressure regulating means including a valve portion for blocking said by-pass to immediately increase the liquid back pressure inside the first member for bulging the side having the thinner gauge.

10. In combination, first and second relatively reciprocable suspension members, said first member comprising a liquid-filled hollow spring member having vertically spaced longitudinal walls of differing gauges, the thicker gauge wall being on the upper side and the thinner gauge wall, being on the lower side of the fluid-tight hollow interior of the first member, a source of normally bypassed circulating liquid having means connectingit to the liquid inside the first member comprising a fitting connected to a relatively static portion of said first member at the top of the upper wall thereof for hydraulically internally bulging the opposite wall of thinner gauge thereby to provide the section modulus of said first member with a changed moment of inertia.

11. In a vehicle, a chassis, an axle assembly, and a leaf spring suspension between said chassis and axle assembly comprising a longitudinally extending leaf member having a longitudinally extending internal fluid pressure chamber with a flexible wall, means providing a source of fluid pressure and connecting it to said chamber, and means responsive to changes in distance between said axle assembly and chassis as permitted by said spring suspension for automatically regulating said pressure in said chamber.

12. In the vehicle defined in claim 11, said last-named means being effective to increase the pressure in said chamber to increase the effective beam cross section of said leaf member and thereby stiffen it as said distance decreases.

13. In the vehicle defined in claim 11, a pump for developing said fluid pressure, and said last-named means comprising automatic valving means connected to the pump outlet.

14. In the vehicle defined in claim 13, a supply conduit between the pump and said chamber, a bypass conduit for said pump connected to said supply conduit, and said valving means being provided in said bypass conduit.

15. A leaf spring assembly comprising substantially laterally and longitudinally coextensive transversely flexible elongate metal members rigidly secured together along their lateral edges so as to form a fluid tight longitudinally extending fluid pressure chamber therebetween, and a fluid pressure inlet to said chamber, one of said members being sufliciently thinner than the other member as to flex to increase the beam cross section of said assembly in controlled response to introduction of fluid under pressure into said chamber.

16. The leaf spring assembly defined in claim 15, wherein said other member is a laterally inflexible spring leaf, and said one member is welded peripherally to said other member.

17. The leaf spring assembly defined in claim 15, wherein said members are integrally joined.

18. The leaf spring assembly defined in claim 15, wherein said other member is at least three times as thick as said one member.

19. In a vehicle having a chassis and at least one transverse axle assembly connected thereto by a leaf spring suspension assembly that is operatively connected to the chassis and said axle assembly, said leaf spring assembly being formed with an internal longitudinally extending fluid pressure chamber having an inlet for introducing fluid under pressure and a flexible wall, a controllable source of fluid pressure connected to said inlet, and means including cooperating means relatively movable with the axle assembly and chassis for automatically controlling the degree of fluid pressure within said cham- .2 2.1 7 her to change the beam cross section of said leaf spring assembly inrespo'nse to changes in relative vertical positions ofsaid axle assembly and chassis. Y In the vehicle defined in claim 19, said leaf sprin assembly being pivotally attached at opposite ends to .said chassis and intermediately attached to said axle assembly.

' 21. In the vehicle .defined in claim 19, said last-named means comprising relatively movable means providing a magnetic field and a sensing device adapted to relatively rnove in said field in response to said positional changes of the chassis and axle assembly, and means actuated by said sensing means for varying said fluid pressure.

22. Inthe vehicle defined in claim 21, a pump for developing saidsource of fluid pressure, and said lastnamed meanscomprising a bypass for the pump outlet, .a valve in said bypass, and an electric motor controlled by. said sensing means for adjusting said valve to vary the outlet fluid pressure of said pump. 7 I In a vehicle assembly, achassis, an axle assembly, a. leaf spring assembly extending longitudinally ofthe vehicle to flexibly suspend said chassis on said axle assembly, said leaf spring assembly comprising at least one elongated spring leafcontaining a longitudinally extending internal chamber having a flexible wall, and means forautomatically-varying the spring rate in response to relative positional changes of the axle assembly and chassis comprising means actuated in response to said changes for varying the fluid pressure in said chamber to thereby vary. the spring leaf cross section.

8 4 24; In a suspension; first and second relatively movable members; said first member comprising an inflatable leaf spring having abulgable wall-portion and a fluidtightinterior; a source of regulated inflating fluidconnected to the interior of said spring; fluid pressure regulating means; and means, efiective as the members move relatively to each other to operate said regulating means to regulate the pressure of the inflating fluid as an inverse function of the distance between the members, comprising cooperating means connected to each of said members, relatively movable with said members and providing a linking magnetic field, and means for sensing said linking magnetic field operably connected to said pressure regulating means.

References Cited in the file of this patent- UNITED STATES PATENTS 1,177,142 Rudd Mar. 28, 1916 2,342,339 Hendrickson Feb. 22, 1944 2,593,040 Lloyd Apr. 15, 1952 2,738,039 Hamilton -2 Mar. 13, 1956 2,756,046 Lucien July 24, 1956 2,762,633 Gouirand Sept. 11, 1956 2,776,830 Gouirand Jan; 8, 1957 2,838,009 Bonanno June 10, 1958 FOREIGN PATENTS 7 Great Britain June 14, 1945 

